1. Field of the Invention
The present invention relates to a method of producing an organic light emitting device (organic electroluminescence device) used for a display, a light source, or an illumination, and more particularly, to a method of repairing a short-circuited site of the organic light emitting device.
2. Description of the Related Art
Recently, in the development of an organic light emitting device (hereinafter, sometimes abbreviated simply as device), an attempt has been made so as to enhance the characteristics of the device. The organic light emitting device is a light-weight self light emitting device, so an apparatus using an organic light emitting device as a display pixel is expected as a next-generation display apparatus. However, for some reasons, when a part of an organic layer between a first electrode and a second electrode is not formed, and the electrodes are short-circuited, pixels (devices) will become non-light emitting devices.
Such a non-light emitting device is formed by a particle (impurity) generated during the formation of a planarization layer, a separating layer, etc., and is also formed by a short-circuited site caused in a plane of the organic layer due to the surface shape of the first electrode.
As a method of repairing a short-circuited site, a laser repair method has been proposed. According to the laser repair method, a short-circuited site in the device is irradiated with a laser to remove an electrode, whereby the short-circuited site is removed, which enables the portions other than the repaired portion to emit light again.
Japanese Patent Application Laid-Open No. 2001-118684 describes a method including, irradiating a second electrode that is a short-circuited site in the case of a device in which a first electrode, an organic layer, and a second electrode are laminated successively on a substrate, thereby removing the short-circuited site of the second electrode, and thereafter, forming a protective layer over the entire surface.
Further, Japanese Patent No. 3817081 describes a method including forming or laminating a fluorine-based or silicon-based resin on a silicon nitride protective layer formed by plasma CVD method as a resin protective layer. In the case where a short-circuit occurs, laser irradiation is performed. However, even if a power is concentrated on a protective layer side due to a focal point displacement or the like, the resin protective layer is unlikely to be damaged so that moisture resistance is kept. Further, the mechanical strength with respect to external collision can also be enhanced by covering the outermost surface with the resin protective layer.
According to the method including forming a protective layer after repairing a short-circuited site as described in Japanese Patent Application Laid-Open No. 2001-118684, sufficient protection performance may not be obtained unless a thick protective layer is formed.
Regarding the repair of a short-circuited site, it is considered to be an efficient repair method to burn out only a conductive member formed in a short-circuited site. However, the following was found by the experiment conducted by the inventor of the present invention. In the case of repairing a short-circuited site by the irradiation with a laser, in order to repair the short-circuited site infallibly, it is insufficient to merely burn out only a conductive member formed in a short-circuited site, and it is necessary to remove the conductive member formed in the short-circuited member. In this case, the conductive member formed in the short-circuited site or constituent materials of other devices scatter onto a second electrode.
More specifically, if the short-circuited site is removed after the second electrode is formed, the particle having scattered when the second electrode is formed, and the constituent material of the device having scattered when the short-circuited site is repaired need to be covered. That is, in order to prevent water permeation, a thicker protective layer is required.
Further, the repair of a short-circuited site as described in Japanese Patent Application Laid-Open No. 2001-118684 is conducted before a protective layer is formed after a second electrode is formed. Therefore, an organic light emitting device is exposed to atmosphere for a long period of time, which may degrade the device before the protective layer is formed.
On the other hand, according to a method including performing the irradiation with a laser after forming a protective layer as described in Japanese Patent No. 3817081, it is difficult for a protective layer made of an inorganic material to deal flexibly with the evaporation of an underlying layer, so the occurrence of cracks and the like cannot be prevented completely. Further, it is difficult to consider that a single resin protective layer has protection performance equal to that of the inorganic protective layer, which may decrease the protection performance after the irradiation with a laser.